The present invention relates to automated monorail conveyance systems for transporting green tires (i.e., unvulcanized tires) within a tire manufacturing factory and more specifically to an elevator system incorporated in the monorail conveyance system for transferring the green tire from a monorail to a tire molding press.
Tire manufacturing factories are arranged into separate areas within which specific tire manufacturing operations take place. Two manufacturing steps having major significance in relation to the present invention are the tire assembly process and the tire curing, or vulcanizing process. These two processes take place in separate locations within a manufacturing operation, typically within a single building of the tire building factory.
In brief summary, tires are assembled in an uncured or unvulcanized state in one part of a factory, and then moved to another part of the factory where they are inserted into heated tire presses wherein the tire is molded under heat and pressure and, in the same process, vulcanized.
More specifically, the tire assembly process involves the use of a tire building machine which includes a cylindrical assembly drum upon which such tire components as the inner liner, the cord-reinforced plies, the beads and the sidewalls of the xe2x80x9cgreen carcassxe2x80x9d are assembled into a cylindrical shape. The green carcass then undergoes an initial xe2x80x9cblow upxe2x80x9d into a toroidal shape more closely resembling a typical tire. The blow-up process typically coincides with the installation upon the green carcass of the belt structure, fabric overlay and tread cap, all of which are typically assembled upon a separate xe2x80x9cringxe2x80x9d into which the green carcass is expanded during the blow-up process. After this initial blow-up process in which the green carcass is joined with the belt structure and tread cap, certain additional tire components are typically added, such as the two shoulder skirts which are applied as uncured rubber layers, each of which lies over one of the two respective circumferential juncture lines where the edge of the tread cap joins with the sidewall. This description of the assembly of a xe2x80x9cgreen tirexe2x80x9d is only exemplary. Other methods of tire assembly can be used, as when, for example, the tire""s sidewalls are assembled upon the green carcass after the blow-up process and after the belt structure and tread cap have been installed upon the toroidally shaped green tire.
After the green tire has been assembled, it must be moved to the port-on of the tire-manufacturing facility or building wherein the tire is molded and cured. The molding and curing are performed in a heated tire molding press in which the external rubber surfaces of the green tire are shaped, as with the tread pattern, under pressure. The tire molding press also heats the tire so as to induce the curing or vulcanizing process during which the previously uncured rubber undergoes thermally induced chemical changes that result in the formation of the kinds of firm, stabilized, shape-holding rubber that is typical of a finished tire.
The two above-described processes are separated in time by the transport of the green tires from the tire assembly area to the location of the curing presses. Often, if not typically, the transport of the green tires involves a layover of the green tires within an intermediate storage area. A given green tire is stored until an appropriate press, one that is suited for that specific type of green tire, is ready to receive the tire. Thus the tires that are assembled in a typical tire-building process are commonly not all of the same type or size. In other words, multiple types of tires are assembled in the tire-building region of the factory. Correspondingly, each different tire type (or size) must be cured in a press that has been set up to receive specific tire types and to shape and cure the specific tire types.
A multiplicity of considerations come into play in the period of time from when the tire is assembled to when it is cured. One consideration is whether or not the tire must be physically transported to the intervening storage area prior to being moved to the curing press. Tire transport typically involves the use of such vehicles as fork-lift trucks or similar wheeled vehicles upon which the green tires can be loaded for transport and then unloaded. Another consideration is that each different tire type must be accounted for and readily retrievable from within the storage area. That is, each green tire must be easily identifiable so that it can be retrieved from the storage area and then transported to the appropriate tire curing press for insertion into the press as soon as the appropriate press becomes available to receive the green tire. Another consideration is that the manufacturing facility must be designed to accommodate the wheeled transfer vehicles, that is, it must have wide surfaces xe2x80x9croadsxe2x80x9d upon which the wheeled vehicles can travel with sufficient room so as to minimize the chances of a collision between the vehicle and stationary objects or with other vehicles or with people. Another consideration is that the storage area must be large enough to accommodate sufficient numbers of each given type of tire so that at no time, ideally, will any curing press or presses be removed from service for want of a tire in need of molding and curing. The storage area also acts as a buffer zone from which a supply of green tires can be withdrawn even if there is a slowdown in the tire assembly process due to disabled machinery or other hold-up problems.
Tires that are moved from the assembly area to the storage area and then to the curing area are labeled in the assembly area. That is, a tag of some sort is put on the tire, identifying its type, size and other parameters which determine the specific curing press type to which it is to be delivered for final molding and vulcanizing. The tag is also placed in such a location on the tire as to indicate the green tire""s proper orientation when it is finally delivered to, and loaded into, the curing press. That is to say, the orientation of the tire within the curing press is not random. Rather the tire is preferably placed in the press at a precise rotational orientation determined by numerous factors that are not specifically relevant to the present invention and are therefore not discussed herein.
The above-described transport, storage, press-loading process and intermediate accounting steps in the tire manufacturing process have traditionally been labor intensive in the physical sense. That is, human beings have been used to manually load and unload the green tires upon the transport vehicles as well as to drive the vehicles. Also, it was necessary to locate specific stored tires, to properly read each tire""s identifying label, to transport the tire to storage or from storage or to the specific curing presses for each specific tire type, and to load the tire into the press according to the angular orientation needed for that specific tire.
Among the challenges presented by the above-described method of operation is the use of wheeled transport vehicles within the same areas used by human laborers, which presents obvious safety hazards. Another challenge is that large portions of the factory floor area are used by the pathways upon which the transport vehicles move. Yet another disadvantage of previous methods of operation is the amount of time consumed in locating and identifying given tire types within the storage area. Still another disadvantage is that manual movement of the tires, to or from transport vehicles in the tire assembly area and in the storage area, can result in damage to the green tires. Furthermore, the use of human labor in the loading and unloading of heavy green tires can lead to musculoskeletal difficulties for the laborers. Finally, the size of the storage area must be large enough to accommodate both people and vehicles as well as to hold a sufficient number of tires so that specific tire types can be readily and rapidly located and retrieved for transport to the appropriate curing presses.
Various methods of automated and computer-managed tire processing methods have been brought into use in recent years. For example, self-guiding trucks have been used to convey green tires that are loaded and unloaded by means of xe2x80x9crobotsxe2x80x9d of various types and capabilities. These trucks are sometimes guided by floor-mounted rail systems, or even by xe2x80x9creadingxe2x80x9d lines that are painted upon the floor areas upon which the vehicles move. In one method, described in U.S. Pat. No. 5,631,028, self-guiding, self-propelled wheeled xe2x80x9cconveyorxe2x80x9d vehicles drive along special roadways. The conveyor vehicles carry xe2x80x9cpallets,xe2x80x9d each of which carries four tires. The tire storage area is actually a pallet storage area within which both loaded and empty pallets are stored. Robot arms are used to move the green tires to and from the pallets, which, at the time of loading or unloading, may or may not be situated upon a conveyor vehicle. Among the disadvantages of such a system is the large proportion of factory floor area needed to accommodate the roadways and the storage areas for pallets that might or might not have green tires on them.
A patent of particular relevance in regard to automated in-factory green tire transport is U.S. Pat. No. 4,268,219 (""219), entitled xe2x80x9cGreen Tire Conveying Method and Apparatus,xe2x80x9d by Nakagawa et al. FIG. 5 in the Nakagawa patent shows a conveyor system that appears to incorporate a monorail, though the term xe2x80x9cmonorailxe2x80x9d is not used per se within the patent. The Nakagawa patent addresses centrally located automated control from a site within the factory. The ""219 patent also refers to the use of a xe2x80x9cdemand signal,xe2x80x9d which is not specified as being by wire or radio, as a communication link with the rail-borne xe2x80x9ctrucks.xe2x80x9d The apparent monorail trucks of the ""219 patent are able to deliver tires directly into the tire presses. The Nakagawa patent also includes a buffer storage area located between the tire-building part and the tire press part of the factory.
It is an object of the present invention to provide an automated monorail transport system as defined in one or more of the appended claims and, as such, having the capability of being constructed to accomplish one or more of the following subsidiary objects.
One object of the present invention is to provide an automated monorail transport system for automating that part of the tire manufacturing process that involves the transport of tires from the location of green tire assembly to the location of the curing presses where the green tires are molded and vulcanized.
Another object of the present invention is to provide an automated monorail transport system to minimize the portion of factory floor area that would otherwise be given over to roadways wide enough to safely accommodate both human beings and powered wheeled vehicles.
Yet another object of the present invention is to provide an automated monorail transport system that maintains a real-time, computer-based accounting of the location in storage or in transport of each green tire according to type and curing press to which it is to be delivered.
Still another object of the present invention is to provide an automated monorail transport system with automated means by which to rotate each green tire to an optimal angular orientation prior to insertion into the tire molding press.
Another object of the present invention is to provide an automated monorail transport system that reduces the number of monorail carriers used to transport green tires from the buffer storage to the curing presses.
Another object of the present invention is to provide an automated monorail transport system that reduces the number of human beings involved in the physical handling, loading and unloading of green tires and to eliminate both the ergonomic problems associated with manual handling of green tires and the potential for manual-induced damage to uncured tires.
Still another object of the present invention is to provide an automated monorail transport system with automated means for identifying and sorting green tires during transport from the tire assembly area to the tire curing/vulcanizing area of the factory.
Another object of the present invention is to provide an automated monorail transport system that incorporates multiple tire-storage buffers between the monorail and the tire press.
A further object of the present invention is to provide an automated monorail transport system that accommodates tire presses of the kind that open vertically.
Yet another object of the present invention is to provide an automated monorail transport system with central computer management of the automated monorail tire transport system.
The present invention relates to automated monorail conveyance systems for transporting green tires (i.e., unvulcanized tires) within a tire manufacturing factory. More specifically, the present invention relates to the transport of a plurality of green tires to a plurality of tire curing presses. It includes a monorail track upon which ride one or more monorail transport carriers. The conveyance system is characterized by one or more elevator systems located near each of the plurality of the tire presses for receiving green tires from the monorail carriers. Each of the elevator systems has an elevator that is vertically moveable for conveying green tires from the monorail carriers to a loader of the tire press. The elevator can ride upon a vertical support rail and includes a supporting arm with a basket mounted at the distal end of the arm. In operation, the basket receives a green tire from a monorail truck at a first location and is then moveable along a vertical path to a second location where the green tire is unloaded from the basket by a loader of the press.
In one embodiment, the supporting arm and basket of the elevator system can be angularly moveable in a horizontal plane about a vertical axis extending through the vertical support rail.
In a second embodiment, the elevator system can also be moveable in horizontal linear translation from the second location to a third location where the tire is unloaded by a press loader.
A tire-grasping portion of each of the monorail carriers can angularly orient each green tire about the tire""s axis such that subsequent angular motions of the elevator system and the press loader are taken into account in delivering the green tire at a predetermined angular orientation to the press. The basket of the elevator system in conjunction with the press loader associated with each press act functions as a buffer storage for the green tires in process.
The present invention is also directed to a method for conveying a plurality of green tires to a plurality of tire-curing presses with one or more monorail transport carriers. The method includes a transferring step wherein each green tire is transferred from one of the monorail carriers to a loader of a tire press. The transferring step includes movement of a green tire along a vertical path from a first location where the tire is transferred from the monorail carrier to an elevator to a second location. The transferring step can include angular movement of the green tire within a horizontal plane from its position at the first location to its position at the second location where the green tire can be transferred to the loader of the press. The transferring step of the present invention can also involve a horizontal translation movement of the green tire from the second location to a third location where the green tire is transferred to the loader of the press.
The method of the invention can also include a step of angularly orienting each green tire about its axis while still being carried by the monorail carrier in such a way that subsequent angular motions while transferring the green tire are accounted for placing the tire in the tire press at a predetermined angular orientation. The method of the invention further includes providing a buffer storage for the green tires between the location where the green tire is transferred to the elevator system from the monorail carrier and the press loader.